The present invention is directed to a razor having more than one shaving aid element.
The incorporation of a shaving aid element in a disposable razor is often desirable. U.S. Pat. No. 4,170,821 (xe2x80x9c""821 patentxe2x80x9d) discloses a razor cartridge with a solid water-soluble shaving aid. The shaving aid can be a lubricant, whisker softener, razor cleaner, medicinal agent, aloe vera, vitamin E, lanolin, and other ingredients or any combination of these. A typical composition of a shaving aid element comprises a hydrophilic polymer and other soluble shaving aids such as those listed above being embedded in a matrix of a hydrophobic polymer. Typically, polyethylene oxide is used as the hydrophilic polymer and polystyrene is used as the hydrophobic polymer. Other compositions are also possible.
The beneficial effect of shaving aids in a disposable razor can be enhanced by incorporating more than one shaving aid element into a razor. A number of prior art patents disclose razors or razor cartridges incorporating two shaving aid elements. However, the disclosed shaving aid elements are positioned on the razor spaced apart from one another on different razor elements. For example, U.S. Pat. No. 5,524,347 discloses a razor cartridge with a first shaving aid element located on the upper surface of a cap member, behind the shaving blades, and a second shaving aid element positioned near the guard member of the razor, forward of the shaving blades. In U.S. Pat. No. 5,369,885, the shaving aid elements are attached respectively to the cap portion behind the shaving blades and to the seat portion forward of the shaving blades.
The beneficial effect of shaving aids in a disposable razor can be enhanced by incorporating more than one shaving aid element into a razor. A number of prior art patents disclose razors or razor cartridges incorporating two shaving aid elements. However, the disclosed shaving aid elements are positioned on the razor spaced apart from one another. For example, U.S. Pat. No. 5,524,347 discloses a razor cartridge with a first shaving aid element located on the upper surface of a cap member, behind the shaving blades, and a second shaving aid element positioned near the guard member of the razor, forward of the shaving blades. In U.S. Pat. No. 5,369,885, the shaving aid elements are attached respectively to the cap portion behind the shaving blades and to the seat portion forward of the shaving blades.
The separation of the shaving aid elements in these patents does not readily permit the benefits of one shaving aid element to be provided in conjunction with the benefits of the other shaving aid element. Thus, there exists a need for a feasible method of manufacturing shaving aid elements and securely coupling such elements to a razor in close proximity to one another.
Regardless of the exact chemical composition used for the shaving aid element, injection molding or extrusion can be used to manufacture shaving aid elements in quantities necessary for mass production. In injection molding, the shaving aid element is co-molded directly in the razor as shown in U.S. Pat. No. 4,778,640. In extrusion, the shaving aid element is extruded in the desired shape and then typically cut to size and secured to the razor as shown in U.S. Pat. No. 4,624,051 (xe2x80x9c""051 patentxe2x80x9d).
U.S. Pat. No. 5,956,848 (xe2x80x9c""848 patentxe2x80x9d), discloses an extruded shaving aid element that has a composite structure. The shaving aid element of the ""848 patent consists of two shaving aid elements that are co-extruded. When secured to a razor cartridge, the composite shaving aid element presents two adjacent exposed lengthwise-extending portions. However, manufacturing such co-extruded structure can pose difficulties during assembly because in many situations, the two co-extruded elements may shrink at different rates during drying or curing and result in bending of the shaving aid element. To overcome this problem, the compositions of the two shaving aid elements may have to be modified with additives which may compromise the effectiveness of the shaving aids.
Another disadvantageous aspect of the composite shaving aid element of the ""848 patent is its non-symmetric cross-sectional shape. The composite co-extruded shaving aid element of the ""848 patent has a three-lobed Y-shaped first element with a second element co-extruded into the upper trough of the Y-shape. Such non-symmetrical shape complicates manufacture and limits the viable storage methods for the stock of shaving aid element before it is used in the razor manufacturing process.
Methods for securing the precut shaving aid element to the razor include mechanical means and adhesives. When mechanical means is utilized, the razor is made with an internal cavity and the shaving aid element is inserted into the cavity as illustrated in the ""051 patent. A tab or any like member retains the shaving aid element in the cavity. The ""848 patent also illustrates a shaving aid element that is mechanically locked into a razor cartridge. In the ""848 patent, the shaving aid element has a ridge running along the bottom side of the shaving aid element which locks into a mating receiving portion of the cartridge. Disadvantages associated with such mechanical method include the need to precisely precut the shaving aid element to close tolerances and to form the shaving aid element from a material with suitable hardness and resiliency for such mechanical connection, as well as the added manufacturing expense and time of producing the tabs or like members. Furthermore, positioning the precut elements in the proper orientation and position for affixing to the razor complicates the manufacturing process.
When an adhesive, such as acrylate adhesive, is used, the shaving aid element and the razor must be properly positioned after the adhesive is applied and clamped together for a period of time to allow a bond to form. Although the curing time can be reduced by the application of energy, such as ultraviolet radiation, this adds another manufacturing step and increases production costs. Furthermore, the ultraviolet radiation may be absorbed or deflected by structural elements on the razor units, thereby preventing uniform curing of the adhesive. In any event, even accelerated cure time decreases manufacturing efficiency. Other disadvantages with adhesives are the added expense of the adhesive and the difficulties associated with the handling of adhesives.
The application of ultrasonic energy to join plastic components has been utilized in many industries. In ultrasonic welding, a solid-state power supply transforms electrical energy to 20 kHz or 40 kHz mechanical energy. A converter changes this electrical energy into ultrasonic mechanical vibratory energy. A horn transmits the ultrasonic mechanical energy directly to the parts to be assembled. A combination of applied force, surface friction, and intermolecular friction at the mating surface between the parts to be joined elevates the temperature until the melting point of the material is reached. Force is maintained after the vibrations cease and a molecular bond or weld at the interface is produced. A more complete discussion of ultrasonic welding is found in the following publications, which are hereby incorporated by reference: xe2x80x9cUltrasonics and Microprocessors Team-up for Efficient Assembly,xe2x80x9d Assembly Engineering, November 1987, and Ultrasonics Plastics Assembly, 1979, published by the Branson Ultrasonics Corporation.
Ultrasonic welding has also been used in the shaving industry. For example, U.S. Pat. No. 5,070,613 describes a razor blade unit with a blade holder secured by a fixation strip ultrasonically welded to a lower portion of the razor blade unit. Further, it is well known to ultrasonically weld a head portion of a disposable razor to a handle portion. However, ultrasonic welding of a shaving aid element has not been suggested or disclosed in the art.
The present invention provides a method of manufacturing a razor imparting various benefits such as the provision of more than one shaving aid element as well as a simplified manufacturing process for attaching the shaving aid elements to the razor. Each shaving aid element may carry a different shaving aid, such that the user is provided with more than one shaving aid.
In accordance with the principles of the present invention, the multiple shaving aid elements are provided in close proximity to one another on a same razor component where the razor component may be a cover, a guard, a blade seat, a blade protector (an element which is selectively positioned over the blade to cover the blade cutting edge), or a handle of the razor. In one embodiment, exemplified in FIG. 1, the shaving aid elements are provided on the cover of the razor, behind the razor blade and spaced apart from each other. Preferably, the shaving aid elements are formed separately from each other. The shaving aid elements may be seated in channels on the surface of the cover. The placement of the shaving aid elements on the same razor component rather than on different razor components processed at different stations simplifies the manufacturing process because placement of the shaving aid elements is then performed at the same assembly station, e.g., only at the cover assembly station.
A number of additional advantages are also provided by the formation of shaving aid elements with a cylindrical cross-section, as in one embodiment of the invention. The rounded surface of cylindrical shaving aid elements allows the shaving aid elements to contact the skin surface at a tangent. This allows the skin and the shaving aid elements to glide easily with respect to each other, resulting in a smooth shaving motion. The cylindrical shape is also optimal for manufacturing because it requires the least amount of adhesion to secure the shaving aid elements in the channels. The seating of the shaving aid elements in channels such that the shaving aid elements protrude minimally from the surface of the cover further enhances the above benefits of a cylindrical shaving element while providing a firm securement of the shaving aid elements with respect to the razor. The protrusion from the razor component of a rounded shaving aid element surface rather than a surface with sharper comers, such as present on the flat shaving aid elements of the prior art, presents a surface less susceptible to dragging forces. As such, lower forces are imparted to the rounded shaving aid element during shaving than are imparted to a shaving aid element with sharper comers, and thus less adhesion is required to secure the rounded shaving aid element in place.
Preferably, if a cylindrical shaving aid element is provided, at least two shaving aid elements should be provided because a cylindrical element imbedded in a channel exposes less surface area than a typical flat shaving aid element. Utilization of more than one shaving aid elements in the present invention compensates for that factor and permits a greater amount of shaving aid to be released during shaving.